Drawn together with Rep. Brad Sherman, Berman is hoping to pick up as many non-Democratic votes as possible in the heavily Democratic district in the San Fernando Valley. The endorsements from the three Senators focused on Berman's foreign policy chops as ranking member of the Foreign Affairs Committee and his ability to work across the aisle.

"Howard Berman is a man of determination and honor," McCain said in a statement released by the Berman campaign this morning. "He works to keep America safe, and our country is stronger with him in Congress."

Sherman, who currently represents far more of the redrawn district than Berman, finished 10 points ahead of Berman in the seven-candidate, all-party primary in June. Berman must overcome that geographic disadvantage to prevail in November.